° 1916 ] Huxley, Bird-watching and Biological Science. 261 



fierce and genuine? (Tits, Thrushes, Mocking-birds) or is it degener- 

 ate, one might almost say merely symbolic? (Blackcock, Red- 

 shank, etc. Selous ('09) has some interesting remarks on this 

 point.) 



(2) Is there fighting between females? (Sylviidse; and I have 

 seen a chase between two female Nighthawks lasting for over 

 thirty minutes.) 



(3) How much of the fighting is due to mere sex-passion, and 

 how much to jealousy proper? In other words, is it directed 

 blindly against all others of the same sex, or definitely against a 

 single intruder who is tampering with the mate's affections? (In 

 the Grebe, jealousy is very strongly developed. We should expect 

 to find jealousy where there is monogamy and mutual courtship. 

 A special form of jealousy is seen in the Blackcock (Selous, '09) 

 where the sight of a hen crouching to a cock rouses the anger of all 

 the other cocks, who immediately rush at the successful suitor. 

 Fighting due to mere sex-passion is seen in many Mammals, in such 

 birds as fight previous to pairing-up, and in the ceremonial fights 

 of such polygamists as the Blackcock.) 



(4) Does jealousy modify the courtship-actions? (In the Crested 

 Grebe, "Shaking" between the members of a pafr after a flirtation 

 by one of them, is of a special type.) * 



(e) Nest-building, Egg-laying, etc.: (1) Do both sexes share in 

 nest-building, or not? If so, do they share equally? 



(2) How long does it take to build the nest? 



(3) How many nests are built? (The Grebe builds two or 

 three, the European Wren ( Troglodytes parvidus) and the American 

 Magpie {Pica p. hudsonia) often four or five.) 



(4) Is there more than one kind of nest? (The Bower of the 

 Bower-bird of Australia is probably a modified nest, while the 

 pairing-platform of the Crested Grebe is undoubtedly so.) 



(5) Is there any form of courtship specially connected with 

 nest-building? (Many birds during courtship carry leaves, twigs 

 and other nest-materials in their beaks — e. g. Sylviidse, Crested 

 Grebe. Others that nest on the ground have displays in which 

 kicking and scraping the earth, pressing or rolling the breast on the 

 earth play a part {e. g. the Ostrich, and the Peewit {Vanellus 

 cristatus); see Selous, '01.) 



